Magnetic core and method of manufacture



Patented July 16, 1929.

unien STATES PATENT OFFICE;

' EHLERS, OF COPENICK, FALKENBEBG, OF BERLIN, GERMANY,

ASSIGNOBS TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

iuaenn'nc oorm'ann uncrnon or MANUFACTURE;

. No Drawing. Applicationflled July 9, 1926, Serial-No. 121,490, and inGermany July 25, 1925.

Our present invention relates to magnetic.

cores such, forexample, as those employed ior telephone repeater coilsor loading coils,

and similar purposes.

' Cores of this generaltype are practice made bywinding fine Wire intorings, by

one another is generally not necessary as the v f thm hlm ofOXlClGfOIIIIBd on the wire Wlll furnish allot the insulation required.In the case of cores'inade up of powdered-mat rial. however, someinsulation is required and this is usually supplied'by employing i'mthebody of-the core a mixture of magnetic and insulating material. Itis-well rec-' ognized, however, that in any of these types of cores themagnet-icand insulating elements I cannot completelyfill the spaceoccupied by. the core. N on-magnetic intermediate spaces ren'min whichare especially injurious when located transversely to the magneticfield; These spacesmay reduce the effective permeability of the core toa considerable extent.

The object of ouninvention is to provide a .niethod whereby thisdisadvantage may largely be overcome. In carrying our invent1on intoeffect, we provide a way of filling these hollow spaces partially-orentirely with magnetic material in order to increase the cll'ectivepermeability. This may be accomplished by impregnating the core afteritsmanufacture by means of a magnetic soluhull or .fuslon. In the-caseof'a core made from pressed powdered material the impregnation ispossible because of the factthat" hands this 18th day of June, 1926.

even after the material has been subjected to high pressure the mas-sisstill permeated by a capillary network of hollow spaces.

As an impregnating medium colloidal so-' lutions of metallic iron ormetallic. iron alloys or other magnetic materials in readily vaporizableliquids are suitable. Preferably the mass'should be repeatedlyimpregnated and dried. The core may in some cases be impregnated infused baths of Heusler alloys, or such alloys may be added in the formof fine powdered material before it is assem bled, and after assemblythis powder can be dispersed by heating' WVhat we claim as new anddesire to secure by Letters Patent of the United States, is

1. The method of increasing-the permeability of magnetic cores formed ofpressed powdered material which consists in filling hollow spaces in thecore after. assembly by particles of magnetic material.

.2. The method of increasing the permeability of magnetic coresWhlCliCODSlStS in impregnating the core body after assembly by immersingit in a liquid containing magnetic material in a form capable ofentering the spaces in the core. 4

3. The method of increasing the permeability of a magnetic core whichconsists in impregnating the core body after assembly in a colloidalsolution of magnetic material and then vaporizing the liquid of thesolution. a

4. The method of increasing the permeability of magnetic cores whichconsists in asscmbling the core and then impregnating the core body witha solution of magnetic material.

5.-The methodof increasing the permea- 8O bility of magnetic coreswhichfconsists in first assembling the core, then nnmersmg the core 4body n a. liquid containing magnetlc material in solution and thenvaporizing the liquid of j v the solution.

' In w1tness whereof. we have hereto set our WALTHE'R EriLERsr FRITZFALKENBERG.

